Hugh Laurie isn’t a bastard, but he plays one on TV. He also plays a doctor, a genius in the art of ”differential diagnosis.” On House — the rookie drama that’s Fox’s biggest scripted hit since 24 debuted four years ago, and has made Laurie its most unlikely breakout star (in America, at least; in his native England, he’s a comedy legend for his work on the sitcom Black Adder) — this means curing maladies that would baffle your average ER white coat. Leprosy, anthrax poisoning, allergic reactions to blue jeans: Give Dr. Gregory House some time — and a couple bottles of Vicodin (his leg, crippled by a blood clot, leaves him in constant agony) — and he’ll diagnose the problem, with a misanthropic panache unseen since vintage Andy Sipowicz. Diseases are neat little puzzles, but patients are a royal pain. Laurie is himself polite where House is politically incorrect, humble where House is arrogant. He’s one of those actors so self-conscious about their acting, they can’t stand to watch themselves on screen. Ask him the secret to House’s success, and he demurs: ”If I actually watched the episodes, maybe I’d know.”

A scalpel-sharp procedural drama in a year when serialized sensations Lost and Desperate Housewives are getting all the attention, House’s ratings success isn’t tricky to diagnose: Call it American Idol syndrome. Before the talent show’s January premiere, House’s vital signs were barely stable — averaging just 6.5 million viewers. But after getting an Idol lead-in on Jan. 18, House (Tuesdays, 9 p.m.) has developed a pounding pulse — the March 22 episode garnered a season-high 17.3 million viewers — and earned an early renewal from Fox. ”My dream was that we’d do good enough to keep going, but not good enough for anyone to notice,” says creator and exec producer David Shore. ”Now I worry we’re going to have one week where we only do the same as last week, and Fox is going to go ‘Uh-oh.”’

The creative origins of House are rooted in pain. In 2003, Fox was in the market for its own Law & Order/CSI cash cow and put its money on a pitch by veteran producers Shore (Hack) and Paul Attanasio (Homicide) — a medical mystery show with a Sherlock doc (”House” is a nod to ”Holmes”), ”a whatdunit, not a whodunit,” says Shore, ”with germs and diseases as suspects and culprits.” As he wrote the pilot, Shore drew upon the memory of a sore hip. The earliest he could get a doctor’s appointment was two weeks. By the time it came, the pain was gone — but he went anyway. ”The doctors were incredibly polite, and I couldn’t help thinking, ‘Why?! I am wasting your time!”’ says Shore. ”Writing House, I fell in love with the idea of a guy who would actually say that to a patient.”

House was further refined when X-Men director Bryan Singer came aboard to helm the pilot. In addition to sterile-cool stylishness and CSI-like trips inside the body cavity, Singer electroshocked the show with some pro-patient, hospitals-are-terrifying empathy. One scene in the pilot — a CT scan is experienced as claustrophobic torture — became a tonal touchstone for the series. ”I was destined for House,” says Singer, who set the show in his hometown of Princeton, N.J. ”I have back problems. I screwed up my hip on X-Men 2. And I’m a hypochondriac. I am medically bizarre.”